1. Technical Field
The present invention relates to methods and compositions for pain relief. More specifically, the present invention relates to topical compositions for pain relief.
2. Background Art
Local anesthetics are used in many medical procedures in order to prevent or relieve pain, itching, and burning for a temporary period of time through the blocking of nerve signals and are advantageous when rapid relief is needed. Examples of procedures that local anesthetics are used in include dental procedures such as teeth cleaning and filling cavities, and minor surgeries. Local anesthetics are of two different types, aminoamides and aminoesters. The aminoamides include articaine, bupivacaine, cinchocaine, etidocaine, levobupivacaine, lidocaine, mepivacaine, prilocalne, ropivacaine, and trimecaine. The aminoesters include benzocaine, chloroprocaine, cyclomethycaine, dimethocaine, piperocaine, propoxycaine, procaine, proparacaine, and tetracaine. Local anesthetics can be used topically or injected. Counterirritants (such as menthol, capsaicin, and camphor) are also used to induce local inflammation in order to reduce inflammation in underlying or adjacent tissues.
More specifically, local anesthetics work reversibly binding to and inactivating sodium channels, which produces the effect of inhibiting excitation of nerve endings or by blocking conduction in peripheral nerves. Sodium influx through sodium channels is necessary for depolarization of nerve cell membranes and propagation of impulses along the course of the nerve. Once a nerve loses depolarization and capacity to propagate impulses, sensation in that area is lost. With local anesthetics, it can take several hours to regain sensation in the nerve area. Side effects of local anesthetics can include the feeling that the area of application is swollen, the sensation of feeling cold or hot, rapid heartbeat, and difficulty breathing.
U.S. Pat. Nos. 5,650,157, 5,709,855, and 6,201,022 to Bockow disclose topical analgesic creams that have superior transdermal absorption and absorption speed. Some otherwise desirable oil compositions derived from natural sources are characterized by an unpleasant odor. Fractions or combinations of such oils may also be so characterized. Stable, deodorized oils may be prepared by adding an amount of a deodorizing agent effective to substantially reduce the odor of the derived oil composition, fraction or combination thereof to that oil composition, fraction or combination. The pharmaceutical topical compositions of these patents contain these stable, deodorized oil compositions and exhibit enhanced penetration properties and achieve enhanced patient response. A composition for preventing or treating inflammation and/or pain by topical administration is disclosed. The composition contains an omega fatty acid in combination with spirulina. Preferably, the omega fatty acid is a mixture of omega-3 fatty acids and omega-6 fatty acids. Omega-3 fatty acids include eicosapentaenoic acid and docosahexanoic acid, and omega-6 fatty acids include gamma-linolenic acid and dihomo-gamma-linolenic acid. The composition can further include pharmaceutically acceptable carriers or diluents, vitamins A and E, and a cyclooxygenase inhibitor such as methyl salicylate. The pharmaceutical compositions can be used to manage pain and/or to treat the underlying ailments. Methods of making such topical pharmaceutical compositions are also discussed.
There remains a need for a safe and effective topical local anesthetic for the relief of pain and also to improve range of motion in individuals suffering from pain.